A pointing entry (a kind of virtual link) represents the mapping between a VMO and its original data. It can be implemented as user-defined deriving procedures.
T. Hochin, M. Harada, M. Nakata and T. Tsuji, "Virtual Multimedia Objects as the Platform of Customizing of Multimedia Data", Proc. Int'l Workshop on Multimedia Software Engineering, Kyoto, Japan, April 1998, pp. 20-27.